Furnace



lApril 5 1932# J. L. McFARLAND FURNACE Filed April '7, 1951 Inventor#Jame L... Mc Falan cl,` ,k

*His Attorney;

GNN

Patented Apr. 5, 1932 UNITED STATES PATENT oFFlcE JAMES L. MGEAELAND, oFscnENEcTADY, NEW YORK, AssIGNon 'ro GENERAL ELEC- mmc COMPANY, AcoaroEArrIoN or NEW Yom:

FURNACE Appli-cation filed April 7, 1931. `Serial No. 528,334.

My inventionrelates to furnaces, more particularly to furnaces providedwith a slot or other opening in one of its walls through which a supportfor the charge extends, and

has for its object a simple and reliable con'- struction vfor thefurnace walls, especially the roof wall of the furnace. t

My invention-is particularly applicable to furnaces of the conveyortype, such as used in baking ,vitreous enamel, in. which. a slot openingis provided in the roof for a: hanger supporting the charge in thefurnace.v It has been found that the refractory bricks adjacent the slothave a tendency to become disl5 placed, probably by expansion andcontraction durlng heating and cooling, into the slot space Where theyobstruct the passage/of the hangers. In carrying out my invention -Iprovide specially shaped bricks and mount the bricks so that they arefreeto expand and contract but are held securely against displacementinto the slot opening. It will .be understood, however, 'that myinvention has general application in the construction of furnace walls,particularly the roof wall.v My invention also comprehends a heat'sealbetween the casing and the furnace refractories. A Y

For a more complete understanding of my invention reference should behad to the accompanying drawings, Fig. v1 of which is a side elevationView partially in section 0f an electric vfurnace embodying myinvention; Fig. 2y is a fragmentary'plan view partly in section of thefurnace shown in Fig. v1; Fig. 3 is an enlarged fragmentary sectionalView y showing details of construction; Fig. Lis a sectional view ytakenalong the lines 4-.4 of

Fig. `3 looking vin the direction of the arrows;

while Fig. 5 is a sectional view takenialong the line 5-5 of Fig. 4looking in the direction ofthe arrows.

' Referringto the drawings, I have shown my invention. in one form asapplied to a U- shaped continuous conveyor furnace such as used'in thebaking of vitreous enamel, although'itwill be understood that myinvention has application to various other types of furnaces. A furnaceof this general type 50 y is described and claimed in the copendingapchamber.

plication of C. L. Ipsenand James L.

land, S. N. 326,833, filed December 18, 1928, and assigned to the sameassignee as this in vention.

As shown, the furnace comprises heat refractory walls 10 forming anelongated heating chamber, the walls being formed of suiti able heatrefractory bricks and enclosed in an outer metallic casing 11. Thefurnace walls are supported on a metallicframework comprising aplurality of vertically arranged I-beams 14 at each side, arranged inpairs having their upper ends connected by hori zontal I-beams 15extending across the top of the furnace. One end of the furnace, asshown' in the left-hand end, is closed by a Wall 16 and this end iselevated and further sup-` ported on horizontal lI-beams 17 extendingunderneath the furnace. This elevated closed end of the furnace servesto entrap the heated air While the opposite lower end remains open forthe passage of the articles to be heated into and out of the furnace. Inthe raised end portion is a central wall 18 made of suitable heatrefractory material which divides t at portion into two chambersconnected together through the passage remain- 'ing between the innerend of this wall, i. e.,

the left-hand end as observed in Fig. 1 of the drawings, and the closedend of the furnace. The articles to be heated` may therefore be passedcontinuously into the furnace along one side of the central wall 18across the closed end and out past the other side of the wall 18. Theinclined portion 19 of the heating chamber serves as a heat exchangechamberwhereby heat is given up from the hot articles passing out of thefurnace along one side of this chamber to the cold incoming articles onthe oppositeside of the In the roof wall of the furnace is a U- shapedslot 20l1aving its two parallel strai ht portions extending' in parallelrelatlon throughout the length of the furnace and its curved portionextending across the closed end. This slot is provided for hangers 21carryingvthe material 22 to be heated. These i nickel and chromium whichare provided with suitable racks 23 on their lower ends for supportingthe material 22. They extend upward through the slot into pivotedengagement with trolleys 24 supported on a track 25, shown as an I-beammounted directly above the slot 20. It will be understood that therewill be a plurality of'hangers 21 and trolleys passing along the tracks,they being connected together to form an endless conveyor. For example,the trolleys may be secured to an endless chain 26 provided` withsuitable driving means whereby the hangers and their loads are passedcontinuously along the track into and out ofthe heating chamber. Inorder to prevent the escape of heat through the slot it is covered by achannel or cap member 2 In accordance with my invention I provide aspecial construction for the refractory bricks and associated supportingparts forming the roof of the furnace. I have shown the roof of thefurnace provided with a layer of special heat refractory bricks 28 whichform the inner lining of the furnace. As shown in Fig. 2 along the sidesof the furnace chamber these bricks are long enough to extend from theside wall of the slot to the outer wall of the furnace. In the middle,i. e., .between the parallel lengths of the slot there are two bricksplacedend to end. Around the curved portion ofthe closed end ofthefurnace tapered bricks 29 are used, as shown in Figs. 2 and 3. Thesebricks are supported on elongated metallic members 30, engaging theiradjacent edges,whereby the bricks are free to expand and contract butare'secured against longitudinal movement into the slot.

As shown the supporting members 30 are U-shaped or channel members. Forthe 'roof support adjacent the side walls these channel members aresecured against endwise displacement by means of bolts 31 (Fig. 2)secured thereto and passing through the walls of the furnace. Thesebolts together with the brick construction forming the side walls of thefurnace support the outer ends of the channel members. Their inner endsare supported by elongated vertical rods or bolts 32 having their upperends secured directly to the cap member 27 or to supporting brackets inturn secured to the cap member, as will be described in detailhereinafter. Suitable recesses are provided in the adjacent edges of thebricks for these rods, or spacing between' the bricks may be great enouh to allow for them. Also there are provider? anchors 33 for the innerends of the bricks which are shown probably most clearly in Figs. 3and4. These anchors 33 are T-shaped members, having apertures in the endsof their Shanks through which the rods 32 extend whereby the anchors aresecured with their Shanks resting in adjacent bricks. The cross bars 33ain the anchors project downward into engagement with the outer ends ofthe bricks so as to effectively Vsecure the bricks against movement inan inward direction, i. e., into the slot opening. i 4

The supporting means for the bricks forming the portion of the roofbetween the sides of the U-shaped slot is quite similar to that justdescribed. Along the central wall 18 the inner ends of the channelsupporting members 30 are supported on this wall, the outer ends beingsupported by rods 32 as before. Around the curved portion at the ends ofthe furnace the supporting members 30 have their inner ends secured to ametallic member 34 so as to extend radially between the tapered orV-shaped bricks 29. The member 34 projects upward from 'the bottom ofthe furnace to which it is secured, for example in the `brickwork at thebottom, and lies against the inner end of the central vwall 18. Theupper end of this member is secured by a rod '35 extending obliquelythrough the roof and secured to one of the horizontal I-beams 15.Bracing links 36 are provided to interconnect the outer ends of thesupports 30 around the curved portion, these links being pivotallyconnected at their ends to the supporting rods 32. Also additionalanchor members 37 are provided, these anchor members being pivotallysecured to the links 36 at the centers thereof.

It will be understood that sufficient space is maintained between thebricks 28 and 29 to allow for expansion 'and contraction due to changesin temperature. The channel support provides for freedom of expansionand contraction, the bricks being free to slide thereon while the anchormembers prevent any movement into the slot opening.

The slotopening is further defined by special upright bricks 38 (Fig. 4)which are set up endwise on the ends of thebiicks 28 and mil 29. Thesebricks are provided with recesses side walls of the slot present smoothsurfaces.

On the outside of the bricks 28, 29 and 38 and between the bricks andthe outer metallic lining is a layer of suitable heat refractoryinsulating material 39 preferably in the form of bricks. A similarconstruction may be used at the bottomv of the furnace. Any suitablesource of heat may be used. As shown an electric heating resistor 40 ismounted on each side of the central wall 18.l

As previously stated, the sup orting rods 32 are secured at their upperend s to the top-y lift or cap member 27 either directly or through themedium of supporting members attached be In other words, this portion ofthe cap member extends over the two sides of the U-shaped groove as wellas the base part of thel groove, 1. e., the left-hand end of the furnaceas seen in F ig.'2. At a point substantially above the left-hand end ofthe central wall 18, as viewed in Fig. 1, this enlarged end portion ofthe cap member connects with two portions 275 eX- tending parallel witheach other over the respective sides of the slot to the open end of thefurnace. The cap member portions are secured directly to the upperI-beam sup-v port 15. They are of substantial construction, preferablyof relatively heavy cast iron. 0n the sides of the slot adjacent theouter walls of the furnace a metallic member 45 is provided,l thismember being secured in turn to the cap member and forming a support forthe upper ends of the rods 32 whereby this part of the roof of thefurnace is supported.`

A similar construction is used for each side of the slot in connectionwith the two narrow cap member portions 276, the metallic channelsupporting members 30 for that portion of the roof wall between theparallel sides of the slot extending across from one slot to the otherand having their ends secured to-the respective cap members. As a resultit will be observed that this central portion of the roof wall betweenthe sides of the slot, that is, the portion to the right of the centralwall 18 as viewed in Fig. 2, is suspended on the cross members.

For supporting the central roof section between the slots underneath theenlarged cap portion 27a special metallic brackets 46 are providedhaving their upper ends se' cured to the cap member and their lower endsforming supports for the upper ends of the rods 32 at this point. Theauxiliary supporting rods 47 forming intermediate supports for thechannel members around the bend extend directly upward into engagementwith the upper wall of the cap member. The auxiliary upright bricks 38defining the slot opening have their. Lipper ends secured by flangemembers 48, one on each side of the slot, which angemembers are in turnsecured to the members 45 or the supporting brackets 46 as the case maybe. These flange members furthermore form Wearing surfaces for the sidesof the slots and prevent injury to the refractories in case the hangers21 swing from side to side. A curved guard'member 49 is provided aroundthe curved portion of the slot against which the trolleys for thehangers bear and whereby the hangers are held cengrally in the slot whenpassing around the Preferably the metallic parts exposed to hightemperatures in the furnace are made of a suitable heat resistingmaterial such as alloy of nickel and chromium or iron, nickel andchromium. This applies especially to the channel supports 30, the links36 and the rods 32 and 47.

Another feature of my present invention is the provision of a heat sealin the metal casing 11 so as to reduce the escape of heat from the slotopening. I have found that a considerable amount of heat escapes by aconduction through the metal of the casing 11, the casing l1 in effectbeing a heat radiator. Furthermore, I have found that there is acirculation of air between the casing and the upper layer of brickswhereby the heated gases circulate between the casing and the upperlayer of bricks and thus heat a large area of the casing which in turnradiates its heat to the air. Also a certain quantity of the heatedgases may escape through crevices in the casing, which may not be gastight. A

In order to reduce this heat loss I provide a flange in the casing nearthe furnace opening, which flange is turned downward and embedded inpowdered heat insulating material, whereby the circulation of the hotgases between the casingand bricks is effectively prevented. Asindicated in Fig. 1 the casing is broken at a point near the slotopening, the adjacentA edges being turned downward in abutting relationas indicated by the reference numeral 50 so as to lie in a groove ordepression 51 provided in the brickwork of the furnace. This groove, ordepression, is filled with powdered heat refractory insulating material52 which thoroughly embeds the down-turned ends of the casing. The twoabutting ends are preferably tightly joined together as by weldingalthough this is not absolutely necessary since the -rigidity impartedby the down-turned edge or fiange serves to hold these portions of thecasing 1n position. It will be observed that thisjoint 1n the vcasingprevents the circulation of heated air underneath the casing since thepowdered insulating material forms a gastight seal around the flange 50formed by the 1. A furnace comprising heat refractory walls forming aheating chamber, one of said by Letters Patent of the United States, is

walls being provided witha slot opening, a plurality of heat refractorybricks defining said slot, kelongated members extending transversely tosaid slot slidably supporting said bricks, supporting means for saidelongated members, and means for preventing movement of said bricks onsaid elongated members into said slot opening.

2. A furnace comprising heat refractory walls forming a heating chamber,one of said walls being provided with a slot, a plurality of bricksdefining said slot, elongated members supporting said bricks at thejunction thereof, a plurality of rods supporting said elongated membersand anchor members for preventing movement of said bricks on .saidelongated members into said slot openin A furnace comprising heatrefractory walls forming a heating chamber, one of said walls beingprovided with a slot, a plurality of bricks defining said slot,elongated members supporting said' bricks at the junction f thereof, aplurality of rods supporting said elongated members and anchor memberssecured to said rods embracing the ends of said bricks adjacent saidslot.

4. A furnace comprising heat refractory walls forming a heating chamberprovided with a curved slot in its roof, said roof being provided with4a plurality of wedgeshaped members defining said slot, channel shapedmembers supporting said wedgeshaped members at the junction thereof anda plurality of heat refractory rods supporting said channel members.

5. A furnace comprising heat refractory walls forming a curved heatingchamber, the

roof wall of said chamber bein provided with a slot, heat refractorybric( members forming said roof, radially extending channel memberssupporting said refractory members at their adjacent edges, connectionsbetween the inner ends of said channel members and said framework, heatresisting rods securing said channels and anchor members secured to saidrods embracing the inner ends of said tapered members.

6. A furnace comprising heat refractory walls forming a heating chamberprovided tion extending into said recess, and powdered heat refractorymaterial in said recess embedding said portion so as to prevent thecirculation of heated gases between said casing and said wall.

9. A furnace comprising heat refractory walls forming a heating chamber,one of :said walls being provided with an opening and with an externalrecess adjacent said opening, an outer metallic casing provided with aflange ortion extending into said recess and pow ered heat refractorymaterial in said recess embedding said flange.

10. A furnace comprising heat refractory walls forming a heatingchamber, one of said walls being provided with an opening and with anexternal recess adjacent said opening,

an outer metallic casing extending from said opening and provided with aflange portion extending into said recess and powdered heat refractorymaterial in said recess embedding said flange 'so as to prevent thecirculation of currents of heated gasses between said casing and saidwall.

In witness'whereof I have hereunto set my hand.

JAMES L. MCFARLAND.

with an opening in its roof, a cap member covering said opening,supporting means for said roof secured to said cap member, andsupporting means for said cap member.

7. A furnace comprising heat refractory walls forming a heating chamberprovided with a curved slot opening in its roof, a cap member coveringsaid opening, metallic supporting rods for said roof secured to said capmember, and supporting means for said cap member.

8. A furnace comprising heat refractory walls forminga heating chamber,one of said walls being provided with an external recess, an outermetallic casing provided with a por-

